The present invention relates to an improved wellhead seal for providing a metal-to-metal seal between the interior of a wellhead housing and the exterior of a wellhead hanger.
Wellhead seals have long been used to seal between the hanger and the housing in which it is supported. An example of a prior art wellhead seal is disclosed in U.S. Pat. No. 3,797,864 which provides an elastomeric ring positioned between metal end pieces having arms extending onto the inner and outer end portions of the elastomeric seal ring and means for compressing the seal axially to cause it to expand radially into sealing engagement with the inner and outer sealing surfaces.
Another type of wellhead annular seal is disclosed in U.S. Pat. No. 4,595,063 which seal includes inner and outer seal rings positioned on inner and outer surfaces of a sleeve and a U-shaped actuator which engages the ends of the seal ring to create a compression in them by virtue of relative movement between the actuator and the sleeve.
U.S. Pat. No. 4,471,965 discloses another type of seal in which an H-shaped member having arms with rounded sealing ends thereon is used for sealing across an annulus.
U.S. Pat. No. 4,178,020 discloses an H-shaped seal member with opposed wedge rings for use in a slip joint to lock the components together and provide an irreversible metal-to-metal seal.
A U-shaped seal which is wedged inward and outward into sealing engagement with the inner and outer walls of an annulus is disclosed in U.S. Pat. No. 4,595,053.
A resilient packing ring which has upper and lower legs which are actuated by wedges is disclosed in U.S. Pat. No. 1,905,122.
Another wellhead annulus sealing assembly is disclosed in U.S. Pat. No. 4,131,287. This structure includes a seal ring with two upper and two lower arms which are forced into sealing position by upper and lower wedges. The assembly is connected into an assembly by bolts which extend through the wedges and into the seal ring.